Soft/hard ferrite nanocomposites: Evaluation of temperature dependent dielectric properties

• Published in: Physica. B, Condensed matter Vol. 627; p. 413581
• Main Authors: Dhabekar, Kalyani, Mohan Kant, K.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.02.2022; Elsevier BV
• Subjects: Chemical precipitation; Co-precipitation; Cobalt ferrites; Composite; Composite materials; Compressive properties; Conductivity; Current carriers; Dielectric loss; Dielectric properties; Ferrites; Mechanical properties; Microwave absorption; Nanocomposites; OLPT; Space charge; Temperature dependence; Conductivity; Dielectric loss; Composite; OLPT; Co-precipitation
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2021.413581

Nanocomposites of cobalt ferrite (CoFe2O4) and strontium ferrite (SrFe12O19) were synthesized with various weight ratios 1:1, 1:2, 1:4, 1:8 and 1:16, by chemical co-precipitation route with higher content corresponding to SrFe12O19. Dual phase refinement employed for the prepared composites and confirms the presence of independent CoFe2O4 and SrFe12O19 phases. The increasing weight fraction of SrFe12O19 in the prepared composites is in accordance with its increasing weight ratio. An increase in compressive strain in the composites was attributed to larger ionic radius of Sr+2 ions. The electrical behavior in the composites was described by Cole-Cole plots at 250 °C from 20 Hz-106 Hz. An increase in impedance with increasing weight ratio of SrFe12O19 was observed, due to creation of effective scattering centers. Conductivity mechanism was explained by Overlapping large polaron tunneling (OLPT) model. A decrease in dielectric constant with increasing frequency is due to decreasing space charge polarization, due to inability of charge carriers to follow the varying ac field. Decreasing trend in dielectric loss for the prepared composites confirms their utility in microwave absorption applications. •Synthesis of nanocomposites of CoFe2O4 and SrFe12O19 in various weight ratios by facile chemical co-precipitation route.•An increase in compressive strain was observed in the prepared composites with increase in weight ratio of SrFe12O19.•Presence of individual phases in the composites was confirmed by Raman spectroscopy.•Electrical behavior studied using equivalent circuit with two networks connected in series.•ac conductivity mechanism for the composites explained on the basis of overlapping large polaron tunneling (OLPT) model.